Changing role of coral reef marine reserves in a warming climate

Graham, Nicholas A. J.; Robinson, James P. W.; Smith, Sarah E.; Govinden, Rodney; Gendron, Gilberte; Wilson, Shaun K.

doi:10.1038/s41467-020-15863-z

Cited by 68 publications

(67 citation statements)

References 53 publications

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“…Despite the observed changes in fish community structure, there was surprisingly no evidence of corresponding significant declines in live coral cover over this period. Likewise, there was no significant shift in the composition of the major substrate categories within each site, even between protected and unprotected areas, similar to observations by Graham et al (2020) in the Seychelles over broadly the same period. Despite a weak (non-significant) shift towards communities with less branching, table, foliose and mushroom growth forms, no overall aggregate changes were observed in benthic form, cover or composition through time from the low initial mean coral cover (following coral bleaching mortality).…”

Section: Benthic Community Compositionsupporting

confidence: 79%

Measuring the long-term success of small-scale marine protected areas in a Philippine reef fishery

Bayley

Purvis

Nellas³

et al. 2020

Coral Reefs

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Tropical coral reefs are subject to multiple pressures from both natural and anthropogenic sources. These pressures have caused widespread declines in reef health, resulting in the increased use of spatial management tools such as marine protected areas (MPAs). MPAs have proven generally effective if well designed and enforced, but there are limited long-term studies investigating how the presence of small-scale MPAs affects fish populations and reef communities. Using a 12-year time series, we found that small-scale (10-50 ha) community-managed MPAs along the Danajon Bank of the Philippines preserved average fish biomass within their boundaries over time relative to surrounding fished reefs. Unprotected areas are, however, showing significant long-term biomass decline. MPAs were also found to preserve more key trophic groups and larger-bodied commercially targeted reef fish families. Fish biomass of piscivore, scavenger and invertivore trophic groups inside individual MPAs is, however, still declining at a similar rate as outside. Surprisingly, longterm benthic cover and growth form composition were not significantly affected overall by MPA presence, despite the sporadic use of highly destructive dynamite fishing in this region. Coral cover has remained historically low (21-28%) throughout the study, following widespread bleaching mortality. While management tempered overall abundance declines, we found that irrespective of MPA presence, there was a generalised decline of both large-and small-bodied fish size groups across the study region, most steeply within the 20-30 cm length fish, and a shift towards proportionally higher abundances of small (5-10 cm) fish. This indicates a combination of over-exploitation, inadequate MPA size and coverage for larger fish, and the lingering effects of the 1998 bleaching event. Generalised shifts in body size and trophic structure reported here could lead to future reductions in fishery productivity and stability and will be further exacerbated unless broader fishery regulations and enforcement is instated.

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Section: Benthic Community Compositionsupporting

confidence: 79%

Measuring the long-term success of small-scale marine protected areas in a Philippine reef fishery

Bayley

Purvis

Nellas³

et al. 2020

Coral Reefs

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“…I concur with myriad prior reports and virtually all coral reef scientists of whom I am aware, that if we do nothing to rein in coastal development and climate change, reefs even as we know them now, in their degraded states, will perish (e.g. Bruno, Côté, and Toth, 2019;Graham et al, 2020;Hughes et al, 2017;Suchley and Alvarez-Filip, 2018) .…”

supporting

confidence: 73%

“…The MPAs that appear to offer some protection against reef degradation are characterized by strict enforcement of restrictions on extraction of reef resources (Roberts et al, 2017). Nevertheless, these efforts are not likely to permit the persistence and resilience of reefs as we know them now due to climate change (Benkwitt, Wilson, and Graham, 2020;Graham et al, 2020;Suchley and Alvarez-Filip, 2018). Present day reefs are already substantially degraded compared to 40 years ago (Hughes et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

Sea urchins, parrotfish and coral reefs in Grand Cayman, BWI: exemplar or outlier?

Sherman

2020

Preprint

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The change in state of Caribbean coral reefs over the last 40 years has been characterized by phase shifts from scleractinian coral cover to macroalgal cover, the loss of structural complexity and a decline in biodiversity. Not only do scientists want to understand these changes, but also predict the future of coral reefs and their capacity for resilience. In particular, the loss of herbivory, due to declines in parrotfish and the sea urchin Diadema antillarum, has been implicated in many studies as a proximate cause of the coral to macroalgal phase shift. However, reports of the particular role of these putative herbivores have varied, with some studies claiming a causal role for parrotfish, others for Diadema and still others suggesting no such relationships. Often these studies just examined one response measure of coral reef biodiversity. In this paper, I report the relationship between parrotfish and Diadema to many metrics of reef organization surveyed simultaneously in the same transects in reefs outside and within the Marine Protected Area (MPA) of Grand Cayman, an island that has been affected by increasing tourism over the last 30 years. The magnitudes of the various measures of reef diversity reported here are consistent with those reported elsewhere. The relationships among those measures are consistent with those reported in some prior studies and inconsistent with others, reflecting the variation in responses documented in prior studies. The presence of sea urchins was associated with survey sites having higher levels of coral cover, lower levels of macroalgae cover, and lower densities of parrotfish than survey sites without sea urchins. Moreover, parrotfish abundance was associated with a decrease in coral cover and little relationship to macroalgae cover. Neither coral cover nor macroalgae cover was different in sites within the MPA compared to sites outside the MPA. I argue that the combination of site-specific local stressors and their interaction with global stressors makes it unlikely that any one island or even regional reef system could serve as an exemplar for Caribbean-wide reef degradation. Moreover, it is difficult to assess the potential for reef resilience in the face of the ongoing assaults from increasing tourism pressures and global climate change.

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“…The evidence that fishing alters the trophic structure of coral reef fish assemblages significantly, to the extent that it can indirectly alter the benthos, remains an open question. Recent literature now emphasizes that human activities can affect trophic structure of coral reef fish assemblages from both “top‐down” (e.g., fishing) and “bottom‐up” (degradation of coral reef benthos, with benthos serving as shelter and food for reef fish) processes (Graham et al 2015, 2020, Russ et al 2015 c , Ruppert et al 2017).…”

Section: Discussionmentioning

confidence: 99%

Coral cover a stronger driver of reef fish trophic biomass than fishing

Russ

Rizzari

Abesamis

et al. 2020

Ecological Applications

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An influential paradigm in coral reef ecology is that fishing causes trophic cascades through reef fish assemblages, resulting in reduced herbivory and thus benthic phase shifts from coral to algal dominance. Few long-term field tests exist of how fishing affects the trophic structure of coral reef fish assemblages, and how such changes affect the benthos. Alternatively, benthic change itself may drive the trophic structure of reef fish assemblages. Reef fish trophic structure and benthic cover were quantified almost annually from 1983 to 2014 at two small Philippine islands (Apo, Sumilon). At each island a No-Take Marine Reserve (NTMR) site and a site open to subsistence reef fishing were monitored. Thirteen trophic groups were identified. Large planktivores often accounted for >50% of assemblage biomass. Significant NTMR effects were detected at each island for total fish biomass, but for only 2 of 13 trophic components: generalist large predators and large planktivores. Fishing-induced changes in biomass of these components had no effect on live hard coral (HC) cover. In contrast, HC cover affected biomass of 11 of 13 trophic components significantly. Positive associations with HC cover were detected for total fish biomass, generalist large predators, piscivores, obligate coral feeders, large planktivores, and small planktivores. Negative associations with HC cover were detected for large benthic foragers, detritivores, excavators, scrapers, and sand feeders. These associations of fish biomass to HC cover were most clear when environmental disturbances (e.g., coral bleaching, typhoons) reduced HC cover, often quickly (1-2 yr), and when HC recovered, often slowly (5-10 yr). As HC cover changed, the biomass of 11 trophic components of the fish assemblage changed. Benthic and fish assemblages were distinct at all sites from the outset, remaining so for 31 yr, despite differences in fishing pressure and disturbance history. HC cover alone explained~30% of the variability in reef fish trophic structure, whereas fishing alone explained 24%. Furthermore, HC cover affected more trophic groups more strongly than fishing. Management of coral reefs must include measures to maintain coral reef habitats, not just measures to reduce fishing by NTMRs.

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Changing role of coral reef marine reserves in a warming climate

Cited by 68 publications

References 53 publications

Measuring the long-term success of small-scale marine protected areas in a Philippine reef fishery

Measuring the long-term success of small-scale marine protected areas in a Philippine reef fishery

Sea urchins, parrotfish and coral reefs in Grand Cayman, BWI: exemplar or outlier?

Coral cover a stronger driver of reef fish trophic biomass than fishing

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